This invention relates generally to plug-in fuse assemblies and more specifically to miniature plug-in fuse assemblies of the type comprising a one-piece fuse element formed of fuse sheet metal and secured to a housing of insulation material.
Miniature plug-in fuse assemblies consisting of a one-piece fuse element formed from fuse metal and secured to a plastic housing have been heretofore developed for use in automotive vehicle circuits. Fuse assemblies of this type have been disclosed in a number of patents including the following U.S. patents:
U.S. Pat. No. 3,909,767--Williamson et al.--Sept. 30, 1975 PA1 U.S. Pat. No. 4,040,175--Williamson et al. --Aug. 9, 1977 PA1 U.S. Pat. No. 4,056,884--Williamson et al. --Nov. 8, 1977 PA1 U.S. Pat. No. 4,131,869--Schmidt, Jr. et al.--Dec. 26, 1978
In the plug-in fuse assemblies of the type disclosed in the aforesaid patents, the fuse element is stamped from relatively thick metal stock to provide terminal prong portions of adequate strength and rigidity. The blade type terminal prong portions are of a substantial width requiring a larger housing than necessary if the terminal prong portions were in the form of cylindrical pins providing equivalent areas of contact surfaces. Other types of plug-in fuse assemblies previously developed have employed terminal prong portions in the form of cylindrical pins secured to a housing but required the mechanical attachment of a separate link or fuse wire to the terminal prong portions. Examples of such fuse assemblies are found in the Heath U.S. Pat. No. 2,537,827 issued Jan. 9, 1951 and in the Borzoni U.S. Pat. No. 3,436,711 issued Apr. 1, 1969.
The Spangler U.S. Pat. No. 3,878,497 issued Apr. 15, 1975 shows a fuse assembly which includes a one-piece fuse element formed of sheet metal. The fuse element comprises terminal receptacle portions of tubular form at opposite ends of a central fuse link portion. This type of fuse element construction is not particularly suitable for arrangement in loop shape with the fuse link portion extending transversely between a pair of laterally spaced terminal portions for use in a miniature plug-in fuse assembly.
In the electrical connector art, it has been found advantageous to stamp and roll tubular terminals from sheet metal. Examples of such tubular terminals are shown in the aforesaid U.S. Pat. No. 2,537,827, in the von Scheven U.S. Pat. No. 1,991,914 issued Feb. 19, 1935, and in the Klumpp, Jr. U.S. Pat. No. 2,861,324 issued Nov. 25, 1958. Electrical connectors are also known which employ tubular terminals stamped from sheet metal and so constructed that they may be assembled and anchored with a plastic housing by mere axial insertion into bores in the housing. Examples of such connectors are shown in the Doty U.S. Pat. No. 2,332,483 issued Oct. 19, 1943 and in the Daenz U.S. Pat. No. 2,353,618 issued July 4, 1944. Connectors of this type are well-suited to mass production techniques at low labor and material costs but the full advantages of such techniques have not been utilized in the manufacture of plug-in fuse assemblies because of the problems presented by the construction and arrangement of the parts comprising heretofore known miniature plug-in fuse assemblies.